h6 shaft tolerance (IT6)
Lower-case h6 is an ISO 286 shaft tolerance class (IT6, es = 0): at Ø10 mm the deviations are 0/−0.009 mm, at Ø25 mm 0/−0.013 mm (upper/lower). Looking for the H6 hole?
Shaft tolerance class h6 per ISO 286-1:2010: fundamental deviation es = 0, grade IT6 (6 µm at ≤ 3 mm to 40 µm at 400–500 mm). For an exact size, open the calculator with h6 selected.
- Type
- Shaft
- Grade
- IT6
- Tolerance
- 6 … 40 µm
- Fund. deviation
- es = 0
h6 limits by size range
| Size (mm) | Upper (µm) | Lower (µm) | Ø max (mm) | Ø min (mm) | Upper (mm) | Lower (mm) | Dev. (in) |
|---|---|---|---|---|---|---|---|
| ≤ 3 | 0 | −6 | 3.000 | 2.994 | 0 | −0.006 | 0 / −0.00024 |
| 3 – 6 | 0 | −8 | 6.000 | 5.992 | 0 | −0.008 | 0 / −0.00031 |
| 6 – 10 | 0 | −9 | 10.000 | 9.991 | 0 | −0.009 | 0 / −0.00035 |
| 10 – 14 | 0 | −11 | 14.000 | 13.989 | 0 | −0.011 | 0 / −0.00043 |
| 14 – 18 | 0 | −11 | 18.000 | 17.989 | 0 | −0.011 | 0 / −0.00043 |
| 18 – 24 | 0 | −13 | 24.000 | 23.987 | 0 | −0.013 | 0 / −0.00051 |
| 24 – 30 | 0 | −13 | 30.000 | 29.987 | 0 | −0.013 | 0 / −0.00051 |
| 30 – 40 | 0 | −16 | 40.000 | 39.984 | 0 | −0.016 | 0 / −0.00063 |
| 40 – 50 | 0 | −16 | 50.000 | 49.984 | 0 | −0.016 | 0 / −0.00063 |
| 50 – 65 | 0 | −19 | 65.000 | 64.981 | 0 | −0.019 | 0 / −0.00075 |
| 65 – 80 | 0 | −19 | 80.000 | 79.981 | 0 | −0.019 | 0 / −0.00075 |
| 80 – 100 | 0 | −22 | 100.000 | 99.978 | 0 | −0.022 | 0 / −0.00087 |
| 100 – 120 | 0 | −22 | 120.000 | 119.978 | 0 | −0.022 | 0 / −0.00087 |
| 120 – 140 | 0 | −25 | 140.000 | 139.975 | 0 | −0.025 | 0 / −0.00098 |
| 140 – 160 | 0 | −25 | 160.000 | 159.975 | 0 | −0.025 | 0 / −0.00098 |
| 160 – 180 | 0 | −25 | 180.000 | 179.975 | 0 | −0.025 | 0 / −0.00098 |
| 180 – 200 | 0 | −29 | 200.000 | 199.971 | 0 | −0.029 | 0 / −0.00114 |
| 200 – 225 | 0 | −29 | 225.000 | 224.971 | 0 | −0.029 | 0 / −0.00114 |
| 225 – 250 | 0 | −29 | 250.000 | 249.971 | 0 | −0.029 | 0 / −0.00114 |
| 250 – 280 | 0 | −32 | 280.000 | 279.968 | 0 | −0.032 | 0 / −0.00126 |
| 280 – 315 | 0 | −32 | 315.000 | 314.968 | 0 | −0.032 | 0 / −0.00126 |
| 315 – 355 | 0 | −36 | 355.000 | 354.964 | 0 | −0.036 | 0 / −0.00142 |
| 355 – 400 | 0 | −36 | 400.000 | 399.964 | 0 | −0.036 | 0 / −0.00142 |
| 400 – 450 | 0 | −40 | 450.000 | 449.960 | 0 | −0.040 | 0 / −0.00157 |
| 450 – 500 | 0 | −40 | 500.000 | 499.960 | 0 | −0.040 | 0 / −0.00157 |
Deviations at the upper end of each range (Ø columns use that size); use the calculator for the exact size. — : not defined by ISO 286 for that size. Upper/Lower (mm) and inch columns are shown on wider screens.
About h6
h6 denotes a shaft tolerance zone with zero line deviation in the ISO 286 system. It is used in H7/h6 (Precisely located parts that can still be assembled and turned by hand: gears on shafts fixed by keys, pulleys, centring flanges.) and F7/h6 (Shaft-basis equivalent of H7/f7.).
At Ø25 mm h6 is 0 / −0.013 mm, i.e. 24.987 to 25.000 mm.
How the limits are calculated
h6 uses grade IT6 (a standard tolerance of 13 µm at 18–30 mm). Fundamental deviation: es = 0: the tolerance zone sits entirely below the nominal size, and IT6 sets its width. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.
h6 in practice
Where it's used
h6 is the basic precision shaft. With es = 0, the largest shaft is exactly the nominal size, and the zone extends downward by IT6. It is the shaft of the shaft-basis system (F7/h6, G7/h6, K7/h6 and so on), a usual tolerance for ground bar and linear shafting, and the partner of H7 in the locational clearance fit H7/h6 for gears, pulleys and centring spigots fixed by a key or a shoulder.
How to check it
Use a micrometer reading to 1 µm, or a snap gauge with GO at the nominal size and NO-GO at the lower limit. Because the GO limit is the nominal size itself, a GO ring gauge of that size is a quick functional check that the shaft will enter any H hole. Measure at 20 °C: at IT6 a hand-warm part reads several micrometres large.
Easily confused with
H6 in capitals is the hole class with EI = 0. h6 is often read as a fit, but Ø30 h6 only tolerances the shaft; the bore class decides whether it slides (H7/h6), locates (K7/h6) or presses (P7/h6). Compared with g6, h6 can give zero clearance in an H7 bore.
Worked example
A Ø30 linear shaft in h6 measures 29.987–30.000 mm (0/−0.013 mm). In an H7 housing bore (30.000–30.021 mm) the clearance is 0.000–0.034 mm: line-to-line at worst, so the housing still locates the shaft without play.